Heavy oils are generally referred to those oils with high viscosity or API gravity less than about 23. Crude oils and crude oil residuum derived from atmospheric or vacuum distillation of crude oil are examples of heavy oils. The origin of high viscosity in heavy oils has been attributed to high asphaltene content of the oils. Viscosity reduction of heavy oils is important in production, transportation and refining operations of crude oil. Transporters and refiners of heavy oils have developed different methods to reduce the viscosity of heavy oils to improve their pumpability. One method includes diluting the heavy oil with gas condensate or a low viscosity oil. Fouling of metal surfaces by asphaltene containing oils is also a problem in heavy oil refining and transportation. One method for mitigating metal surface fouling is the use of anti-fouling additives or blending with non-asphaltene containing oils. These methods of reducing viscosity and metal surface fouling tendency of heavy oils require the use of substantial amounts of low viscosity oils that are often expensive and difficult to readily obtain especially at locations where the heavy oils are produced. There is therefore a continuing need for new and improved methods for reducing viscosity and surface wetting tendency of heavy oils. The instant invention addresses this need.